U.S. patent number 5,340,424 [Application Number 07/989,386] was granted by the patent office on 1994-08-23 for method for making disposable pants.
This patent grant is currently assigned to Uni-Charm Corporation. Invention is credited to Michiko Matsushita.
United States Patent |
5,340,424 |
Matsushita |
August 23, 1994 |
Method for making disposable pants
Abstract
This invention effectively avoids the inconvenience conventially
occuring such that, with the pants of prior art being put on the
user, the front body is displaced downward under a force exerted
thereon as the user's legs move or under a weight of excretions
accumulated in the crotch area of the pants, resulting in loosened
leg-openings through which leak of excretion may occur. A front
body comprising a sheet having elastic stretchability in the
transverse direction and a rear body comprising a sheet having no
elastic stretchability are bonded to each other with a transverse
dimension of the front body in its transversely contracted state
being smaller than a transverse dimension of the rear body so that
laterally opposite waist sides of the user's body wearing the pants
may be covered by a part of the rear body.
Inventors: |
Matsushita; Michiko
(Iyomishima, JP) |
Assignee: |
Uni-Charm Corporation (Ehime,
JP)
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Family
ID: |
16345561 |
Appl.
No.: |
07/989,386 |
Filed: |
December 11, 1992 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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903163 |
Jun 24, 1992 |
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Foreign Application Priority Data
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Jul 10, 1991 [JP] |
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3-195702 |
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Current U.S.
Class: |
156/164;
604/385.24; 156/163; 156/227; 156/256; 2/400; 156/267; 156/229;
156/204 |
Current CPC
Class: |
A61F
13/496 (20130101); A61F 13/49011 (20130101); A61F
13/491 (20130101); A61F 2013/49087 (20130101); Y10T
156/1062 (20150115); Y10T 156/1015 (20150115); Y10T
156/1051 (20150115); Y10T 156/108 (20150115); A61F
2013/5666 (20130101) |
Current International
Class: |
A61F
13/15 (20060101); A61F 13/56 (20060101); A61F
013/15 (); B32B 031/08 () |
Field of
Search: |
;156/164,160,163,229,204,227,256,267 ;604/385.2 ;2/400,406 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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A-0048011 |
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Mar 1982 |
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EP |
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A-0405575 |
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Jan 1991 |
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EP |
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A-0417766 |
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Mar 1991 |
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EP |
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A-2354064 |
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Jan 1978 |
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FR |
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960367 |
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Jun 1964 |
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GB |
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2195230 |
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Apr 1988 |
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GB |
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Primary Examiner: Aftergut; Jeff H.
Attorney, Agent or Firm: Philpitt; Fred
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a division of U.S. Ser. No. 07/903,163 filed
Jun. 24, 1992, pending.
Claims
What is claimed is:
1. A method for forming disposable pants, said method comprising
the steps of:
(a) moving an elongated first web (22) along a first path, said
first web (22) having spaced apart longitudinal side edges,
(b) moving an elongated second web (23) along a parallel second
path, said second web (23) also having spaced apart longitudinal
side edges,
(c) said first web (22) having elastic stretchability and being
maintained in a stretched condition while moving along said first
path,
(d) said second web (23) having substantially no elastic
stretchability,
(e) overlapping one longitudinal side edge of said first web (22)
with one longitudinal edge of said second web and bonding said
overlapping longitudinal side edges together along a first seal
line (7) while maintaining said first web (22) in a stretched
condition to thereby form an enlarged third web (30) that is larger
than either said first web (22) or said second web (23),
(f) folding said enlarged third web (30) in two along a
longitudinal imaginary center line (15) and then sealing this
folded web (33) transversely thereof at regular intervals to form a
folded web (33) with a plurality of spaced apart second seals
(8),
(g) cutting said folded web (33) along a plurality of cut lines
(14) that are parallel to each of said second seals (8) to thereby
obtain individual pants with portions of said second seals (8)
remaining along the laterally opposite sides thereof; and
(h) partially cutting off folded web (33) along spaced apart
portions of said longitudinal imaginary center line (15) to thereby
form leg-openings (5) immediately after the formation of said
folded web (33) or during the step of cutting said folded web (33)
into individual pants, the individual pants resulting from the
method having a front body (2) formed from said first web (22) and
a rear body (3) formed from said second web (23), said front body
being smaller in area than said rear body (3) because said first
web (22) has resumed an unstretched state.
2. A method for forming disposable pants, said method comprising
the steps of:
(a) moving an elongated first web (22) along a first path, said
first web (22) having spaced apart longitudinal side edges,
(b) moving an elongated second web (23) along a parallel second
path, said second web (23) also having spaced apart longitudinal
side edges,
(c) said first web (22) having elastic stretchability and being
maintained in a stretched condition while moving along said first
path,
(d) said second web (23) having substantially no elastic
stretchability,
(e) overlapping one longitudinal side edge of said first web (22)
with one longitudinal edge of said second web and bonding said
overlapping longitudinal side edges together along a first seal
line (7) while maintaining said first web (22) in a stretched
condition to thereby form an enlarged third web (30) that is larger
than either said first web (22) or said second web (23),
(f) laying a fourth web (31) having substantially no elastic
stretchability on said enlarged third web (30) to form a composite
web (32),
(g) folding said composite web (32) in two along a longitudinal
imaginary center line (15) and then sealing the resulting folded
web (33) transversely thereof at regular intervals to form a folded
web (33) with a plurality of spaced apart second seals (8),
(h) cutting said folded web (33) along a plurality of cut lines
(14) parallel to each of said second seals (8) to obtain individual
pants with portions of said second seals (8) remaining along the
laterally opposite sides thereof; and
(i) partially cutting off said composite web (32) or folded web
(33) along spaced apart portions of said longitudinal imaginary
center line (15) to thereby form leg-openings (5) immediately after
the formation of said composite web (32) or said folded web (33) or
during the step of cutting said folded web (33) into individual
pants the individual pants resulting from the method having a front
body (2) formed from said first web (22) and a rear body (3) formed
from said second web (23), said front body being smaller in area
than said rear body (3) because said first web (22) has resumed an
unstretched state.
3. A method as recited in claim 2 which further includes the step
of sandwiching liquid absorbent cores between said third (30) and
fourth webs (31) in areas corresponding to the individual pants
before folding said composite web (32) in two as set forth in step
(g).
Description
BACKGROUND OF THE INVENTION
The present invention relates to disposable pants, for example, in
the form of training pants for babies, pants type diaper or
sanitary pants, and method for making them.
For the conventional disposable pants, for example, disposable
training pants, it is well known to form the entire front and rear
bodies from elastically stretchable sheet material such as nonwoven
fabric or to form only opposite side portions of the front and rear
bodies from such sheet material.
However, all of such well known pants are elastically stretchable
at least along laterally opposite sides and, in consequence, the
front body is apt to be displaced downward under a force exerted
thereon as the user's legs move or under weight of excretions
accumulated in a crotch area of the pants. Such downward
displacement of the front body results in not only unsighted
appearance of wearing but also loosened leg-openings through which
leak of excretions may occur.
SUMMARY OF THE INVENTION
It is a principal object of the invention to configure pants using
an elastically stretchable sheet so as to minimize said downward
displacement of the front body.
The object set forth above is achieved, in accordance with the
present invention, by disposable pants comprising a front body made
of a sheet having elastic stretchability at least in the transverse
direction and a rear body made of a sheet having substantially no
elastic stretchability, which are bonded to each other with a
transverse dimension of said front body being smaller than a
transverse dimension of said rear body so that laterally opposite
waist sides of the user wearing the pants may be covered by a part
of the rear body. If it is required for the pants, e.g., training
pants or diaper of pants-type, to absorb and hold excretions, for
example, urine, liquid-impermeable sheets may be used as outer
sheets of the front and rear bodies, respectively, while a single
non-bonded continuous liquid-permeable sheet having substantially
no elastic stretchability may be used as an inner sheet common to
the front and rear bodies, and a liquid absorbent core may be
sandwiched between these inner and outer sheets, if desired.
While, according to the present invention, elastically stretchable
members may be provided, if desired, around the waist-opening and
the leg-openings of the pants in order to tighten these areas, use
of such elastically stretchable members is not essential to the
invention.
With the pants of the invention being put on the user, the
laterally opposite sides of the user's waist are covered by a part
of the rear body having substantially no elastic stretchability and
a transverse contractile force of the front body extending between
said laterally opposite sides of the user's waist and having
elastic stretchability at least in the transverse direction causes
the entire pants to fit around the user's body. Said laterally
opposite sides function as means to hold the pants on the user's
body. The front body located on the user's belly side freely
contracts as the user breathes out.
BRIEF DESCRIPTION OF THE DRAWINGS
The pants constructed in accordance with the present invention and
the method for making them will be described by way of example in
reference with the attached drawings, in which:
FIG. 1 is a perspective view showing pants constructed according to
a first embodiment of the method of the present invention;
FIG. 2 is a partial plan view illustrating some steps followed by
said first embodiment, i.e., bonding a front body web and a rear
body web together to form a web for an outer sheet of the pants,
providing this web for the outer sheet with elastically stretchable
members around a waist and legs, respectively, laying a web for an
inner sheet of the pants on said web for the outer sheet, and
forming leg-openings;
FIG. 3 is a partial plan view of the web assembly shown in FIG. 2
as having been folded along a longitudinal center line and provided
at desired locations with seals for opposite sides of the
individual pants;
FIG. 4 is a plan view of the individual pants obtained by cutting
the web of FIG. 3;
FIG. 5 is a partial plan view illustrating some steps followed by a
second embodiment of the method of the present invention, i.e.,
bonding the front body web and the rear body web together to form
the web for the outer sheet of the pants, providing this web for
the outer sheet with elastically stretchable members around legs,
and further providing said web for the outer sheet with an
absorbent core;
FIG. 6 is a partial plan view illustrating one step followed by
said second embodiment, i.e., providing said web for the inner
sheet of the pants with an elastically stretchable member around
the waist;
FIG. 7 is a partial plan view showing the web of FIG. 6 laid on the
web of FIG. 5;
FIG. 8 is a partial plan view of the web shown in FIG. 7 as having
been folded in two along a longitudinal center line and formed with
leg-openings; and
FIG. 9 is a combination of a partial plan view of the web shown in
FIG. 8 as having been provided at desired locations with seals for
laterally opposite sides of the pants and a plan view of said web
as having been cut to obtain individual pants.
PREFERRED EMBODIMENTS OF THE INVENTION
Embodiment of the Pants
Referring to FIG. 1, the most basic pants I constructed according
to the method of the invention is illustrated.
The pants 1 comprise a front body sheet 2 which is elastically
stretchable at least in the transverse direction (or both in
breadth and length) and a rear body sheet 3 which is not
substantially elastically stretchable. The pants have a
waist-opening 4 and a pair of leg-openings 5. In FIG. 1, the front
body sheet 2 is shown to be contracted in the transverse direction
and, at such state, has a transverse dimension smaller than that of
the rear body sheet 3. The front body sheet 2 is smaller than the
rear body sheet 3 also in a longitudinal dimension. Longitudinal
ends of the front and rear body sheets 2, 3 are overlapped on and
bonded to each other by a continuous seal line 7 extending along
such overlapped area. Respective transversely opposite sides of the
front and rear body sheets 2, 3 have their inner surfaces
overlapped on and bonded to each other by respective intermittent
seal lines 8 extending along these overlapped areas.
With the front body sheet 2 being contracted in the transverse
direction as in FIG. 1, laterally opposite sides 9 of the pants 1
are defined by a part of the rear body sheet 3 and the bonded areas
(seal lines 8) of said laterally opposite sides 9 lie on the belly
side. Obviously, the front body sheet 2 is laterally stretched and
then contracted again as the pants 1 are put on the user.
Transverse dimensional ratio of the front body sheet 2 and the rear
body sheet 3 as well as transverse elongation rate of the front
body sheet 2 are selected so that said bonded areas 8 as well as
said laterally opposite sides 9 may be positioned as mentioned just
above once the pants have been put on the user.
Elastically stretchable members 10, 11 each comprising a plurality
of thread-like elastic elements are attached in their
longitudinally stretched states around the leg-openings 5 and the
waist-opening 4, respectively.
Though not shown, a single continuous inner sheet which is common
to the front and rear bodies and has substantially no elastic
stretchability may be dot-bonded at desired intervals to the inner
side of said front and rear body sheets 2, 3, if desired, so as not
to interfere with the elastic stretchability of said front body
sheet 2. In this case, a liquid-impermeable sheet is used as said
outer sheet while a liquid-permeable sheet is used as said inner
sheet and laterally opposite sides of said inner sheet are bonded
to said laterally opposite ends of the front and rear body sheets
2, 3 in the manner as has previously mentioned. Also in this case,
a liquid absorbent core may be sandwiched between the inner and
outer sheets, if desired.
Embodiment 1 of the Method for Making the Pants
Referring to FIGS. 2 through 4, respective steps in the method of
the present invention are illustrated. A front body web 22 having
elastic stretchability at least in the transverse direction is
transferred to an assembly station (not shown) as said web 22 is
longitudinally stretched by a desired elongation rate, for example
1.05 to 1.5 times, while a rear body web 23 having a width
appropriately larger than said web 22 and having substantially no
elastic stretchability is transferred to said assembly station so
that one longitudinal side edge of said web 23 may be overlapped on
one longitudinal side edge of said web 22 which is being stretched
and this overlapped area may be bonded together by the continuous
seal line 7 so as to provide web 30 defining the outer sheet. Such
bonding may be achieved by using hot melt adhesive, or thermal or
supersonic welding technique.
Stretching of said web 22 may be achieved, for example, as
conventionally employed in stretching of the elastically
stretchable members to be attached around the respective
leg-openings of disposable diaper or the like, by increasing the
circumferential velocity of one pair of nip-rolls located upstream
with respect to the direction in which said web 22 is transferred
to nip said web therebetween and thereby to transfer it, relative
to the circumferential velocity of the other pair of the similar
nip-rolls located downstream.
Two continuous elastically stretchable members 10a, 10b each
comprising a plurality of thread-like elastic elements are placed
on and attached to the web 30 traveling toward said assembly
station along the central while said members 10a, 10b are
longitudinally stretched by a desired elongation rate, for example
1 to 3 times so that the respective members 10a, 10b describe sine
curves partially crossing each other. Simultaneously, another pair
of continuous elastically stretchable members 11a, 11b each
comprising a plurality of thread-like elastic elements are placed
on and attached to said web 30 along the areas adjacent
longitudinally opposite side edges.
Placement of the elastically stretchable members 10a, 10b, 11a, 11b
in the configuration as mentioned above may be achieved, as
disclosed by the applicant of this application in European Patent
Application No. 0405575 A1, by utilizing a pair of traverse means.
Attaching of these elastically stretchable members to the web 30
may be achieved by previously applying hot melt adhesive on the web
30 along loci to be described by the respective elastically
stretchable members or by applying such adhesive directly on these
elastically stretchable members. The portions of the respective
elastically stretchable members 10a, 10b defined between a pair of
adjacent crossings thereof may be free from adhesive so that these
portions are not attached to the web 30 and, in addition, each of
said portions may be cut at one location so that these portions may
be snapped back.
An inner sheet web 31 having a substantially same width as the web
30 traveling toward said assembly station and having substantially
no elastic stretchability is put on and bonded to said web 30 to
form a web 32. Such bonding may be also achieved by use of hot melt
adhesive, or thermal or supersonic welding technique.
From each annular zone 13 defined by the elastically stretchable
members 10a, 10b, a portion 16 having a desired size and a shape
being symmetric with respect to an imaginary center line 14
extending across the web 32 transversely of the traveling direction
of said web 32 is cut out to form each of the leg-opening 5.
The web 32 thus formed with the leg-openings 5 is folded in two
along a longitudinal imaginary center line 15 with the web 31
facing inward and provided with intermittent seal lines 8 extending
adjacent each of said imaginary center lines 14 and thereby the web
31 and the web 32 are bonded to each other so as to form a web
33.
The web 33 being moved toward said assembly station is successively
cut together with the elastically stretchable members 10a, 10b,
11a, 11b along respective said imaginary center lines 14 each
extending in parallel and between each pair of adjacent seal lines
8 and thereby the individual pants are obtained.
Each of the leg-openings 5 may be formed, instead of forming them
immediately after formation of the web 32, immediately after
formation of the web 33 or during operation of cutting the web 33
into the individual pants.
The outer sheet web 30 may be made of liquid-impermeable material
such as plastic film and particularly the web 23 making a part of
the web 30 may be made of moisture-permeable and air-permeable
material. The inner sheet web 31 may be made of fibrous nonwoven
fabric. It should be understood that, as has been described in
reference with FIG. 1, the most basic configuration of the pants
does not use the inner sheet web 31, i.e., only the web 30 is used
as the material for the component sheets of the pants and, in such
cases, the webs 22, 23 forming together the web 30 may be
preferably of nonwoven fabric. While the elastically stretchable
members 10, 11 may comprise natural or synthetic rubber or the
like, these elastically stretchable members are sometimes
eliminated in the most basic pants 1.
Embodiment 2 of the Method for Making the Pants
This embodiment 2 is similar to said Embodiment 1 except that a
liquid absorbent core 34 performed in an hourglass-shape is placed
between each pair of adjacent annular zones 13 defined by the
elastically stretchable members 10a, 10b, as indicated by a chain
line in FIG. 5, before the web 31 is put on the web 30; the
elastically stretchable members 11a, 11b are placed on and bonded
to the inner surface of the web 31, as shown in FIG. 6; and each
leg-opening 5 is formed, as apparent from FIGS. 7 through 9, by
partially cutting off the web 32 after it is folded in two along
the longitudinal imaginary center line 15. Therefore, the parts
corresponding to those said in Embodiment 1 are designated by the
same reference numerals as those designating the corresponding
parts in Embodiment 1 and this Embodiment 2 will not be further
described in details. The core 34 preferably comprises crushed pulp
mixed with thermoplastic fibre and super absorption polymer powder
and molded into a desired shape.
With the pants of the invention put on the user, opposite waist
sides of the user's body are covered by a part of the rear body
having substantially no elastic stretchability and a transverse
contractile force of the front body defined between said opposite
waist sides and having elastic stretchability at least in the
transverse direction causes the entire pants to fit around the
user's body. Thus, these opposite waist sides function as means to
hold the pants on the user's body and thereby to avoid the
inconvenience conventionally occurring due to unstable
stretchability of said opposite waist sides such that the front
body is displaced downward under a force exerted thereon as the
user's legs move or under weight of excretions accumulated in the
crotch area of the pants, resulting not only in unsightly
appearance of wearing but also in loosened leg-openings through
which leak of excretions may occur.
The pants having such advantages can be easily made by the method
according to the invention by overlapping one longitudinal side
edge of the second web for the rear body having substantially no
elastic stretchability on one longitudinal side edge of the first
web for the front body having the elastic stretchability at least
in the transverse direction while said first web is longitudinally
elongated, and then providing this overlapped area with the seal to
bond these webs to each other.
* * * * *